The United Nations is to investigate claims of sexual abuse by its peacekeepers after conceding that recent cases involving its soldiers in the Democratic Republic of Congo may not be isolated to that country and similar abuses have probably happened elsewhere.

The United Nations is to investigate claims of sexual abuse by its peacekeepers after conceding that recent cases involving its soldiers in the Democratic Republic of Congo may not be isolated to that country and similar abuses have probably happened elsewhere.

An internal UN report is expected to recommend for the first time that any peacekeepers accused of sexual molestation will not be allowed to return home until they have been prosecuted in the country where the behaviour is said to have been committed. Their own militaries would have to conduct the court martials.

The report, being prepared by Jordan's UN ambassador, Prince Zeid al Hussein, will aim to end the present arrangements under which accused soldiers are allowed to return home to face trial. Many are never prosecuted so offenders can go unpunished. The UN also wants to identify publicly countries whose soldiers face sex charges.

The UN, already reeling from multiple scandals, notably involving alleged corruption in the management of the oil-for-food programme in Iraq, knows it must take firm action to address the Congo debacle as quickly as possible. Instances of abuse in the country began to come to light last May.

The UN's envoy to Congo, William Lacy Swing, an American, is expected to offer his resignation tomorrow when he arrives in New York to confer with the UN secretary general, Kofi Annan. Mr Swing has not been accused of any direct involvement, but senior UN officials have concluded it would be better to have a change at the top in the country.

The UN is bracing for more cases to surface from peacekeeping missions in other countries, including Burundi, Sierra Leone, Ivory Coast and Haiti. "We think this will look worse before it begins to look better," Jane Holl Lute, assistant secretary general for peacekeeping operations, said. "We are prepared for that."

Officials have been investigating 150 allegations against 50 of the 11,000 peacekeepers in Congo. They are accused of paying children as young as 13 for sex. There have also been accusations of rape and gang rape of the people they are meant to be protecting.